<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 群组 */
        p,div,a{
            font-size: 30px;
            color: red;
            background-color: pink;
            margin: 2px;
            padding: 2px;
            display: block;
        }
    </style>
</head>
<body>
    <!-- 群组,这几个群众是一组 -->
     <p>我是一个p</p>
     <div>我是个div</div>
     <a>我是一个a</a>
</body>
</html>